The stochastichyperfine interactionmodelinglibrary(SHIML) simulates fluctuatinghyperfine interactions. It was originally limited to a single spin state. This summer, the code was modified to include an option for a second spin state, allowing it to now simulate Mössbauer spectroscopy experiments. Preliminary testing generated Mössbauer spectra that mimic expected behavior, but more rigorous testing is still needed before releasing this new version to the public. The changes increase the versatility of the library by enabling analysis of data from a wider range of experimental techniques.

1. [1] M. O. Zacate,W. E. Evenson, “StochasticHyperfine InteractionsModelingLibrary,”ComputerPhysics
Communications 182,1061-1077 (2011).
Simulating Mössbauer Effect Using SHIML
Chad M. Johnston and M. O. Zacate
The stochastichyperfine interactionmodelinglibrary(SHIML) isa collectionof computer
routineswritteninthe Cprogramminglanguage [1]. Itwas createdto assistresearchers quicklyanalyze
experimental datathatare influencedby fluctuatinghyperfineinteractions. The original versionof
SHIML onlysupportedexperimental techniquesthatmeasure asingle probe spinstate. Thisleavesout
Mössbauerspectroscopy whichisan importantexperimentalmethod usedtomeasure fluctuating
hyperfine interactions.
Thissummer,we modifiedthe code toinclude anoptionfora secondspinstate. Thisrequired
newroutines,whichwe developedusingthe originalsingle spinstate routines astemplates, toreadand
performthe correct operationsonthe new spinstate. We have alsowrittenanexample programto
demonstrate howSHIMLcan nowbe usedto simulate Mössbauerspectroscopy. We didthisby
modifyingcode developedoriginallytosimulate perturbedangularcorrelationspectra. We hadto add
the abilitytoreadMössbauer-specificparametersandchange the spectral function to 𝐺 𝐿( 𝜔) =
Re [∑ ( 𝑔 𝐿) 𝑞
1
1
2
Γ−𝜆 𝑞−𝑖( 𝜔+𝜔 𝑞)𝑞 ]. Where ( 𝑔 𝐿) 𝑞 is a functionof eigenvectorsof the Blume Matrix,which is
calculatedbythe newversionof SHIML. Gamma (Γ) is the natural linewidth; alsoλq andωq are the real
and imaginarypartsof the eigenvaluesof the Blume Matrix.
Preliminarytestinghasgenerated Mössbauerspectrawhose behaviormimics
expected/publishedspectra. However,more rigoroustestingisrequiredbeforethe secondversionof
SHIML isreleasedforpublicuse. The changesthatwere made thissummerhave increasedthe
versatilityof the library. NowusingSHIMLresearcherscanquicklyanalyze datagatheredfromamuch
widerrange of experimental techniques.